Preheat the oven to 170 degrees C. Line a 21cm x 11cm loaf pan with baking paper, leaving enough paper to hang over two sides of the pan for easier unmolding.

Put the flour, bicarbonate of soda, cocoa powder, sugar, butter, eggs, vanilla and sour cream into a food processor and blitz until smooth. Pour the boiling water down the funnel of the processor and pulse briefly until you have a smooth batter. Using a spatula, stir in the chocolate chips.

Pour the batter into the prepared pan and bake for about 1 hour. A cake tester should come out with a few crumbs clinging to it when it's done.

Make the Syrup:

As the cake is nearing the end of it's cooking time, put the cocoa, water and sugar in a small saucepan and bring to boil over a medium heat. Boil for 5 minutes until, ummm.... syrupy.

As soon as the cake comes out of the oven, poke holes all over the top with a skewer and pour the hot syrup all over it. Let the cake cool in the tin for about 20 minutes then unmold and leave to cool completely on a wire rack. Sprinkle the top of the cake with dark chocolate shards.